Does diclofenac increase the risk of cervical necrotizing fasciitis in a rat model?

Non-steroidal anti-inflammatory drugs (NSAIDs) are known for aggravating in vitro infections and were reported in many cases of cervical necrotizing fasciitis (CNF). We developed a rat model of CNF, mimicking as closely as possible the human-CNF, to study the effect of a NSAIDs, diclofenac, as a promoting factor. Twenty rats were injected bilaterally in the neck with peptostreptococcus and with a fresh saliva specimen for another 20 rats. Half of each group was given an intramuscular injection of 4 mg/kg diclofenac at the time of inoculation and 24 h later, and the other half saline injections; rats were killed at day 7 and clinical, bacterial and histological studies were performed to assess the infectious process and the incidence of CNF. No statistically significant difference was found between groups treated with diclofenac vs. the saline injection groups. However a significant correlation was noted between clinical observation, bacterial density and histological signs of inflammation. CNF has a high mortality rate and the use of NSAIDs in conditions potentially leading to CNF is very common. However, our rat model does not support the hypothesis of a promoting role of diclofenac which was occasionally suggested in the medical literature. This study suggests that diclofenac does not seem to increase the risk of occurrence of CNF. Nonetheless, NSAIDs can mask inflammatory signs of an already spreading CNF.